Frederick Gottemoeller - Bridgescape LLC

The community needed bridges that increased traffic capacity and maintained the heavily used pedestrian connection to the spa while improving the attractiveness of the downtown sidewalks and buildings adjacent to the bridges and recognizing the town's historic architectural character. In addition to crossing the river, on the north side of the river the bridges cross the spa parking lots and Interstate 70. On the south side of the river the bridges cross Seventh Street and the two-track mainline of the Union Pacific railroad at a point just west of the historic Glenwood Springs station. The river is enjoyed by kayakers and is a source of great interest to pedestrians crossing the river. Pedestrians also enjoy observing the daily stops of the Amtrak's California Zephyrs, one eastbound and one westbound.

The structural system for the vehicular bridge consists of three trapezoidal weathering steel box girders. The tapered sides minimize the width required at the tops of the piers for the bearings. Each pier consists of three octagonal shafts with no pier caps. This avoids the lengthy pier caps that would otherwise be required because the skew angle gets quite extreme at the northernmost piers. The structural system for the pedestrian bridge consists of two haunched weathering steel rectangular box girders. The girders supply space for the multiple utilities that cross the river. At the piers octagonal shafts pass outside of the box girders to provide visual continuity with the columns of the roofs over the overlooks at two of the pier locations. The overlooks are placed between the railroad and the river and on the centerline of the spa pool. The girders are supported by a concrete cross girder between the pier shafts. The arched soffit of the cross girder emulates the architectural features of the elevator tower.

The community's visual goal was to tie the nineteenth century spa buildings north of the river more tightly into the urban structure of downtown south of the river. With this in mind all of the octagonal pier shafts on both bridges are oriented in plan so that their axes are parallel to the downtown street grid. As a further assertion of visual order, the bottom elevation of the red sandstone pier facing is always at the same level, roughly the same as the sidewalk elevation of Seventh Street, which borders the south bank of the river but which is clearly visible from the north bank. Below that level the concrete pier shafts are left exposed. The overall effect is that the stone pier shafts rest on a series of concrete plinths, the tops of which are all on one horizontal plane. That plane becomes a visual base for the structure, one that is at the same height as the downtown's street grid. Finally, the red sandstone on the upper parts of the columns visually tie together the historic buildings on both sides of the river.

As the south end of the vehicular bridge descends to the level of the street grid the vertical clearance available under the vehicular bridge varies from roughly 14 feet at Seventh Street to barely 8 feet at the south abutment. In order to keep the structural depth of this section to an absolute minimum it is built as a full-width post-tensioned concrete slab. The underside of the slab is coffered to minimize the weight of the slab as well as to give it visual interest for people using the space under the bridge. Also, the edges of the slab are tapered to encourage the penetration of daylight into the space under the bridge. This space is also provided with special lighting to promote the use of the area for events and to discourage vandalism.

The city of Glenwood Springs limited the closure period between the demolition of the old bridge and the opening of the new vehicular bridge to the 60 day lull between tourist seasons. This will require constructing the river spans on falsework west of the existing bridge and rolling them into place after the existing bridge is demolished. This also requires building the concrete slab portion of the bridge at its south end within the 60 day period. The pedestrian bridge is required to be in service at all times, which requires building the new pedestrian bridge in the very narrow gap between the exiting vehicular and pedestrian bridges. These requirements significantly limited the design options available for the project.

Mr. Gottemoeller was aesthetic advisor for the vehicular bridge, for the pedestrian bridge and for the elevator tower.